Härmä, A., “Ambient telephony: scenarios and research challenges”, Proc. INTERSPEECH 2007, August 2007 gives an overview of the technical challenges in developing a full-scale ambient telephone for the home environment. An ambient telephone is a speakerphone system based on arrays of loudspeakers and microphones, which are distributed in the home environment and are connected to each other via a home network. The system can receive calls from any source via a central device connected to the Internet, cellular phone network, and possibly the traditional land line. The audio rendering can be performed in a spatially selective way. For example, a user can carry on a conversation with another such that the other appears to be moving smoothly with the talker from one room to another, or such that there are several simultaneous connections open and the contacts are rendered in spatially separate positions in the home environment. The possibility of moving a call from one device and one spatial location to another is one of the central features of the ambient telephone.
In scenarios in which several simultaneous connections to remote callers are open at any one time, some remote callers may not actually be present at any given time. It would be useful if the ambient telephone system could adapt to changing use requirements without substantially complicating its use.